全文获取类型
| 收费全文 | 3816篇 |
| 免费 | 1756篇 |
| 国内免费 | 160篇 |
专业分类
| 安全科学 | 547篇 |
| 废物处理 | 114篇 |
| 环保管理 | 736篇 |
| 综合类 | 2648篇 |
| 基础理论 | 656篇 |
| 污染及防治 | 555篇 |
| 评价与监测 | 203篇 |
| 社会与环境 | 126篇 |
| 灾害及防治 | 147篇 |
出版年
| 2025年 | 47篇 |
| 2024年 | 125篇 |
| 2023年 | 189篇 |
| 2022年 | 225篇 |
| 2021年 | 217篇 |
| 2020年 | 228篇 |
| 2019年 | 219篇 |
| 2018年 | 215篇 |
| 2017年 | 268篇 |
| 2016年 | 287篇 |
| 2015年 | 261篇 |
| 2014年 | 258篇 |
| 2013年 | 355篇 |
| 2012年 | 343篇 |
| 2011年 | 298篇 |
| 2010年 | 206篇 |
| 2009年 | 211篇 |
| 2008年 | 162篇 |
| 2007年 | 255篇 |
| 2006年 | 200篇 |
| 2005年 | 175篇 |
| 2004年 | 128篇 |
| 2003年 | 141篇 |
| 2002年 | 108篇 |
| 2001年 | 95篇 |
| 2000年 | 68篇 |
| 1999年 | 71篇 |
| 1998年 | 49篇 |
| 1997年 | 52篇 |
| 1996年 | 47篇 |
| 1995年 | 39篇 |
| 1994年 | 34篇 |
| 1993年 | 25篇 |
| 1992年 | 12篇 |
| 1991年 | 18篇 |
| 1990年 | 10篇 |
| 1989年 | 11篇 |
| 1988年 | 7篇 |
| 1987年 | 18篇 |
| 1985年 | 5篇 |
| 1982年 | 5篇 |
| 1981年 | 7篇 |
| 1980年 | 5篇 |
| 1979年 | 7篇 |
| 1978年 | 4篇 |
| 1977年 | 4篇 |
| 1976年 | 3篇 |
| 1972年 | 2篇 |
| 1971年 | 3篇 |
| 1970年 | 3篇 |
排序方式： 共有5732条查询结果，搜索用时 8 毫秒
71.
通过对边坡稳定分析方法中的条分理论和响应面法的研究,针对边坡可靠性计算往往没有明确的解析表达式,以及稳定性系数计算方法和响应面法(RSM)的特点,将响应面法中的有限元数值模拟以条分模式中的稳定性系数隐式方程的迭代计算方法代替,建立了条分模式下的边坡可靠性计算的极限状态方程,从而形成了一种新的边坡稳定可靠性响应面分析方法。本文提出的改进的响应面法原理简单,计算效率较高并具有一定的精度,适用于对边坡可靠度的近似计算。 相似文献
72.
73.
地球系统科学提出前我国科学界的某些思维 总被引：1，自引：0，他引：1
列举了在1988年美国提出"地球系统科学"前我国学者在该领域的某些思维:人与天地相应的观点,东亚大陆磁异常与我国人群健康关系的观点,天地生三位一体的观点,地球表层学的观点以及灾害系统的观点等.这些观点虽不如"地球系统科学"着眼于全球整体,但也包括了很大的系统,且不空洞. 相似文献
74.
本文把趋势面分析的数学方法应用于土壤重金属污染调查研究中,使重金属含量分布、污染情况等众多信息集中反映在一张图上,结果令人满意。同时结合当地重金属输入、输出情况,建立了动态平衡模式,计算出该区重金属的土壤环境动容量,并进行了土壤环境预测,为综合治理土壤污染提供了科学依据。 相似文献
75.
直接利用华北ＧＰＳ监测网各个测点的位移观测值,借助高斯型位移协方差函数通过最小二乘配置建立连续分布的位移函数,并根据应变与位移的偏导关系,对华北ＧＰＳ监测区１９９２～１９９５年、１９９５～１９９６年最大剪应变及面膨胀连续分布进行估算,得到其应变场动态图像。 相似文献
76.
对\"地球表层概念\"的界定与发展和基于新概念的地球表层系统(结构)等进行了综合讨论和阐述;定义了地球表层概念的内涵,提出:地球表层是指地表和近地表各圈层相互作用和渗透的地球部分,是地球上部多态(固、液、气、生物和有机态)物质相互渗透、交融并不断进行物能交换、转化和作用而结合形成的具有内部协同性和一定系统结构的有机整体,是地球生物的生存环境和地表生态系统发生、发展和演化的基础;进一步确立了地球表层的空间位置和范围(外延),即包括地球表面上下的岩石圈、水圈、大气圈、生物圈和物理(能量)场及其相关作用在内的地球空间,其下界是软流圈(以软流圈为过渡层),上界为大气圈最外层,至少应包括磁层在内;岩石圈以下的地幔和地核与大气圈以外的宇宙空间均为地球表层的环境. 相似文献
77.
《International journal of occupational safety and ergonomics》2012,18(1):71-79
The current study aimed at comparing the correlation coefficients between wet-bulb globe temperature (WBGT) and a number of parameters, including the discomfort index (DI), modified discomfort index (MDI), predicted mean vote (PMV), predicted percentage of dissatisfaction (PPD), predicted heat strain (PHS), physiological strain index (PSI) and physiological strain index heart rate (PSIhr). In total, 30 workers of a pelletizing factory participated in this study. Environmental parameters and workers’ physiological parameters were measured in 10 working stations. The results showed that effective WBGT (WBGTeff) strongly correlates with DI, MDI, PMV, PPD, PHS, PSI and PSIhr. WBGTeff had the highest correlation coefficients with PMV, MDI, PHS and PSIhr. Based on the obtained results, it was concluded that heat stress exceeded the standard limit for a number of indices in some of the working stations. Thus, some controlling measures should be taken to reduce heat stress in these stations. 相似文献
78.
Jasreet Kaur;Amandeep Singh Pannu;Muhammad J. A. Shiddiky;Xiaodong Wang;Paul Frasca;Jose Alarco; 《Advanced Sustainable Systems》2024,8(6):2300610
To address the fundamental challenge of resource sustainability and to effectively deal with issues pertaining to supply chain resilience, cost efficiency, environmental impact, and the ability to meet specific local needs; there is an urgent need for high-grade battery anode materials produced locally from readily available raw materials. In this work, synthesis of high-quality graphitic carbon (GH) derived from human hair is demonstrated using an in-house engineered reactor based on Joule's Flash heating method. The GH is characterized using various techniques to examine its chemical composition, particle morphology, crystallinity, and demonstrate its usability as an anode material for lithium-ion batteries. Fabricated coin cell with active material exhibits a gravimetric capacity of 320 mAh g−1 at a current density of 30 mA g−1 (equivalent to a C rate of ≈0.1C) over the 100 cycles. The in situ and ex situ studies using XRD, Raman, XPS, and UPS techniques conclude that during the initial charge cycle for GH, lithium ions diffused into the electrode during the resting period are effectively removed. This not only improves the lithium inventory to start with but also mitigates subsequent solvent degradation during solid electrolyte interphase (SEI) formation. Thus, these improvements ultimately enhance the capacity of the anode to 500mAh g−1 at a current density of 20 mA g−1. The study offers the potential to initiate a new realm of research by redirecting the focus to a material once considered as mere waste. 相似文献
79.
Yang Guo Muhammad Javed Xiaoyan Li Shixiong Zhai Zaisheng Cai Bi Xu 《Advanced Sustainable Systems》2021,5(1)
Solar‐driven interfacial water evaporation is a promising strategy to produce clean water by effectively converting abundant solar energy into localized heat. However, many previously reported interfacial evaporation systems are separate and costly. In this work, an all‐in‐one interfacial water evaporator with flexibility, low‐cost, and large‐scale production based on electrostatic flocking technology is proposed. Hydrophilic microfibers (flocks) are vertically planted on the upper side of the textile substrate to enhance the light trapping for photothermal conversion and lower the latent heat for more efficient evaporation. On the other side of the textile, a highly dense and vertically aligned array of hydrophobic flocks are prepared to form a continuous air layer, reducing heat conduction from absorber to bulk water. Taking advantage of those features, the all‐in‐one evaporator achieves a good evaporation rate of 1.32 kg m−2 h−1 for pure water and 1.10 kg m−2 h−1 for seawater. Simultaneously, the evaporator demonstrates resistance to salt accumulation, resulting in its stability in brine. This all‐in‐one evaporator represents an innovative way for designing interfacial evaporators and a convenient approach to mitigate the global freshwater scarcity. 相似文献
80.
《Greenhouse Gases: Science and Technology》2017,7(4):745-755
To achieve better well control for supercritical carbon dioxide drilling, a mathematical model was presented to investigate the pressure and temperature profile in both the tubing and the annulus. The closed model fully couples the hydraulics, heat transfer, and compressibility of carbon dioxide, and then the wellbore flow field is presented and analyzed based on field application. The results show that the pressure change of carbon dioxide is 36.7% smaller than that of water along the annulus in the study case. Carbon dioxide changes into supercritical state when the depth equals 700 m ∼830 m in the tubing, and it could maintain in supercritical state in the whole annulus. Both the pressure profile and the temperature profile are highly coupled with the physical properties of carbon dioxide. The density of carbon dioxide is large enough to drive downhole motors and its capacity is much larger than that of air in the wellbore. The pressure increases lightly with increasing mass flow rate in the annulus; however, it is significantly and positively impacted by the outlet pressure. The influence of outlet pressure on temperature profile is negligible in the tubing. The inlet temperature could not impact the pressure profile in the annulus, and its influence on temperature profile mainly lies in the shallow section of the tubing. It is newly validated that supercritical carbon dioxide drilling is more suitable for the exploitation of unconventional reservoirs with narrow pressure windows. The results could lay a theoretical foundation for practical application. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd. 相似文献